Definitions of what is primary or secondary differs across the disciplines. For the sciences, this is how we would define the different types of sources:
Primary source literature in the sciences:
documents the results of original research
is written by those who have conducted the research
includes firsthand information about their methodologies, data, results, or conclusions.
Secondary source literature in the sciences:
summarizes, compares, critiques, or interprets the primary literature.
Tertiary sources in the sciences:
are collections of primary and/or secondary sources.
Characteristics of primary sources in the sciences include:
Report original research, ideas, or scientific discoveries for the first time
Report results/findings/data from experiments or research studies
May also be referred to as primary research, primary articles, or research studies
DO NOT include meta-analyses, systematic reviews, or literature reviews - these are secondary sources
Are frequently found in peer-reviewed or scholarly journals
Should explain the research methodology used (randomized controlled trial, etc)
Frequently include methods, results, and discussion sections
Are factual, not interpretive
